ULSTER coach Mark Anscombe has warned his side not to lose their focus ahead of Friday night's return to the Pro12 when they host Zebre at Ravenhill (7.05).

Despite Ulster's maximum-point haul from their Heineken Cup double-header with Treviso, and the fact that Zebre were humiliated 64-3 by Saracens at the weekend, Anscombe sent out a clear message that his side must not underestimate the lowly Italians.

Ulster appear to have come through Saturday's 35-3 win over Treviso reasonably unscathed, though Roger Wilson is a pressing concern -- the No 8 picked up an ankle injury and will be assessed later this week.

"The Christmas period is going to be a defining part of the season, and we've got to be really careful if you look at our next five games," said Anscombe, highlighting the forthcoming Pro12 clashes with Leinster and Munster and crunch European ties against Montpellier and Leicester Tigers.

"You could put all your focus on that and then Zebre quietly slip in and you underestimate them and they can do a job on you. We only played them a couple of weeks ago and that was one hell of a battle.

"We've got to be on our toes to make sure that we treat them with the respect they deserve and get that job done before we start worrying about the others."

Regarding their European situation -- Ulster lead Pool 5 by three points from the Tigers -- Anscombe added: "Nothing's changed and it's still going to be one hell of a task to go to Welford Road and get a result. But the fact is that we're in control."

Second-row Lewis Stevenson has returned to full training after his medial ligament injury and could be involved on Friday.

Tommy Bowe has also stepped up his rehabilitation and could be back in mid to late January, while the recovery of Rory Best, Nick Williams, Iain Henderson and Chris Henry continues to be assessed.

Anscombe looks set to rest several of his front-line stars for this week's game as fourth-placed Ulster prepare for a hectic festive period.

This looks likely to mean starts for Paddy Wallace -- after two games for the Ravens following his nine-month absence -- as well as outings for Declan Fitzpatrick and Ricky Andrew against Zebre in what will be Ulster's fourth consecutive game against Italian opposition.

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